The present invention relates to the solubilization of tellurium and to the use of cyclodextrins to accomplish the same, particularly in the mid-pH range. The resulting compositions are useful in many industrial applications, including, but not limited to, applying tellurium coatings to metallic surfaces.
As disclosed in copending application Ser. No. 361,087, tellurium ion sources can be used to apply tellurium-containing coatings to metallic surfaces. Unfortunately, because of solubility limitations, such processes are generally run at either high or low pH's. This is necessary because tellurium ions are generally insoluble in water in the mid-pH range.
It is therefore an object of this invention to provide water-soluble tellurium compositions and a method for solubilizing tellurium in the mid-pH range. This object is accomplished by utilizing a cyclodextrin a solubilizing agent. While it is believed that any cyclodextrin can be used, .alpha.-, .beta.- and .gamma.-cyclodextrins are preferred and .beta.-cyclodextrin is most preferred. The instant dextrin/tellurium compositions and method allow the use of tellurium solutions in the mid-pH range.
The MERCK INDEX, Eleventh Edition, discloses that cyclodextrins act as complex particularly in the study of enzyme action, and that tellurium is a reagent which produces a black finish on silverware.
Co-pending application U.S. Ser. No. 361,087 discloses the use of tellurium-containing compositions to apply tellurium-containing coatings to metal substrates. The use of cyclodextrins as solubilizing agents in such compositions is not disclosed.
These references do not disclose or in any way suggest the instant invention. In fact, no prior art relating to the use of tellurium in combination with cyclodextrins is known to the inventor.